The present invention relates to printers and printer media and more specifically to a method for operating a printer with special printer media (paper) to enhance printer performance.
Duplex printing has become widely available and has provided the capability to produce printed pages having printing on both sides. However, two-sided printing is not required for all applications. Increasing the speed or rate of printing usually requires improvement in the equipment. Accordingly a need exists for a process for increasing printing speed without having to design new equipment.
Turning now to FIG. 1, there is shown typical high speed, high volume printer system for printing continuous forms in which the invention may be advantageously used. The printer system 100 is a continuous form printer such as the IBM 3900 family of printers. Printers in this family employ both pin feed or tractor type feeding mechanisms and also support for pin-less type feed mechanisms. The printer system 100 includes an optional preprocessing device 101 for holding a roll of continuous feed print stock. A printer 103 for printing on the print stock and a post processing unit 109 for processing printed stock. FIG. 2 illustrates a printing system 200 arranging two printers from FIG. 1. in a series configuration for duplex printing. The two printers, a first printer 203 and a second printer 206 are separated by a buffer-flipper unit 204. The buffer-flipper unit 204 takes the continuous print stock exiting from first printer 203 and turns over the print stock before threading it through second printer 206. First printer 203 prints on one side of the continuous print stock and printer 206 prints on the second side of the print stock.
Referring to FIG. 3, there is shown another duplex printer in which the invention may be advantageously used. The printer 10 is a web-fed duplex printer such as the IBM 3170. It comprises a paper supply unit comprising paper reel 11, a splicing table 12, a heated roll 13, a paper cooling unit 14, and a paper conditioning sensor 15. The following processes occur in the paper supply unit.
The operator first inserts an axle in the core of the paper roll 11 and then places the roll in the paper supply using a small hand truck. The paper supply has no paper-driving function; instead, the web is pulled from the paper supply into the print tower. A brake system keeps the paper web at a certain tension between the reel and the first web drive motor. The brake system also detects when the amount of paper remaining on the roll is low.
When a roll is finished, or when you decide to change paper before the roll is finished, you will splice the leading edge of the new roll to the trailing edge of the old roll.
Moisture influences print quality. Thus, the paper supply includes a paper-conditioning system that uses a heated roll to dry the paper to a certain moisture content. After drying, the paper temperature is reduced by the cooling unit. The entire system is controlled by a paper conditioning sensor. When printing stops, the paper is immediately pulled away from the heated roll to avoid scorching the paper.
The printer 10 also includes a print tower portion comprising a first web drive motor (speed motor) 16, print stations 17, a top roller 18, a fuser 19, a paper cooling unit 20, a second web drive motor 23, a cutter 22, and an output stacker 25.
The print tower has eight print units, four for each side of the paper. Each unit prints one of the four "process" colors, cyan, magenta, yellow, and black (CMYK). After the paper passes through the eight print units, it goes over the top roller 18, which directs the paper toward the fuser 19. The non-contact fuser 19 affixes the eight toner layers to the paper. Because the temperature of the paper is high when it leaves the fuser, it passes a paper cooling unit 20, which blows cooled air on the paper's surface. Other printers having duplex capability may also be used with the invention.
The paper web is driven by two motors (16 and 21), which are accurately controlled to maintain a constant web speed and tension. This constancy provides a stable register (the correct positioning of the four color layers on top of each other and the positioning of the image on the front of the paper as compared to the back).
Before the paper leaves the print tower, it passes the cutter 22, where it is cut perpendicular to the paper movement. The paper is then transported by a conveyer to the output stacker 23.